Chemical treatment



Patented Mar. 19, 1946 cnnmcAL-ram'rrmm John w. Latchum; Jr., Bartlesville, okra, is.

signor to Phillips Petroleum Company, a corporatlon of Delaware Application October s, 1542, Serial No. 460,859

No Drawing.

14 Claims. (Cl. 260-6835) This invention relates tohydro'carbon conversions; and more particularly to. the purification ofiluidreaction eiiluents from hydrocarbon conversions carried out in the presence of an anhy.' .drous. normally solid or liquid metal-halide of the Friedel-Crafts type which is readily volatilizable or highly soluble in the eflluent and in the presence of anhydrous hydrogen halide,

which eflluents contain hydrocarbons, usually both the original and the product hydrocarbon in addition to any lay-products, volatilized metal halide and hydrogen halide, as well as other ora identity is not ganic material'whose chemical clearly understood at present.

Still more particularly the invention relates to isomerization of normal paraflins to the corresponding iso-paraifins, and especially of nor-' mal butane to isobutane, by means; of a metal halide catalyst of the type referred toabove and in the presence of anhydrous hydrogen halide.

usually corresponding to the metal halide catalyst.

Usuallylthe metal halide catalyst is an economical and highly satisfactory process of purifying the reaction efilue'ntsfrom hydrocarbon conversionsof the type outlined-above. An-v other object is to effect removal of the volatilized catalyst from vaporous effluentsj of the above type. Still another object is to effect rernoval of the dissolved .catalystfro'm liquid eflluents ofthe type described above; Another object is to purify the reaction efiluents insuch'manner as to remove. not only-"the; catalyst contained" therein, but also the major" part or all of the organic material other than pure hydrocarbon,

I fluent is for the most part not removed there-f 20.

including complexes formed between the metal halidecatalyst and hydrocarbons and other compounds whose exact chemical nature is at prescut but little understood. Another object is to' provide'a, processor \the type --'set forth above wherein the hydrogen halide in the reaction effromfbut is left in the residual hydrocarbon,

, which is a distinct advantage -since this very valaluminuni halide, generally aluminum chloride or bromide. Even more specifically the inven-- tion relates to such a process wherein the reaction .eflluent leaves the isomerization unit in the,

vapor or liquid phase and is subjected to a puri- 'uable hydrogen halide may. be very easily jrecovered from the treated hydrocarbon'for recycle' J to theconversion. Numerous other--ob ects' will hereinafter appear.

' In accordance ;with the present invention, a

' reaction eilluent of thetype-described in detail flcation treatment to remove therefrom the vola- .tilized or dissolved-metal halide catalyst contained therein and the organic material other than paraflins, while allowing thehydrogen halide to remain unaffected.

above'is purifie by treatment with a liquid phosphoric acid. I. ing the eiliucnt, preferably immediately-following the catalyst chamber; witha liquid phos- At the 'present time. hydrocarbon conversions enacted with the aid by the difliculty that the catalyst permeates the entire system causing numerous troubles including corrosion, further reaction, clogging, etc.- This is especially objectionable in those sections of the equipment which follow .the conversion unit. Thus, where theellluent is removed in the. vapor phase and, as is almostinvariably the case where catalysts of the type described above are used, where the catalyst is readily volatilizable, the eiliuent contains substantial quantities of vaporized catalyst, and 'this'catalyst in proc- Iesses heretofore practiced deposits in the equipment after the converter. Again; where the effluent is removed in the liquid phase, it containssubstantial quantities of dissolved or dissolved and suspended catalyst which The principal object of my invention is to provide a process overcoming the foregoing diflicub' I ties. Another object is to provide a convenient,

of aluminum chloride or the likemetal halide catalyst, are' characterized 8 phoric acid, the'metal halide catalyst contained therein is substantially completely orentirely removedthereirom. .At the same time nonydrocarbon organic material: of but little understood nature such as complexes or metal halide. with hydrocarbon, eta, is also removed in substantial entirety. l r

A distinct "advantage of this purification method isthat the hydrogen halide'content of; the eilluent is substantially unaffected bythe phosphoric acid with the, result that it passes throughjthe'treatmentalong with the hydrocarbon product and unconverted hydrocarbon contained in the eiiluent. Only that small amount of hydrogen halide required to saturate the phosphoric acid treating medium is removed from the eilluent, the entire amount of hydrogen causes difliculties in subsequent processing.

halide passing through unchanged after this saturation. W

As thevliquid phosphoric acid employed as the absorbent in my invention,-' I prefer to use a normally liquidacid, particularly aqueous orthophosphoric acid containing at least 15% or'water, 1. e. ranging from 85% 1111 04 down to 50% ve discovered that upon treather.

or even more. dilute. -Any of the commercially available gradesmay be used namely the 50%,

75% or 85% acids. I prefer the 85% orthophosphoric acid of commerce since it contains the least water of any of the commercially available grades.

Instead of orthophosphoric acid, I may use other normally liquid phosphoric acids such as tetraphosphoric acid which contains no free water and which is now commercially available.

Another phosp'horic acid which may be used is pyrophosphorlc-acid which likewise contains no water except that of chemical combination.

' While for purposes of convenience in handling the acid absorbent used should be liquid at ordinary atmospheric temperatures, I may use a phosphoric acid which-is solid at-such temperatures but attains the liquid state at the temperature of the absorption.

For carrying out the treatment of the eiiiuent, I may use any convenient equipment such as a packed column, a bubble-type. column or any other means commonly used for scrubbing a gas with'a liquid absorbingunedium or for effecting intimate liquid-liquid contacting. I

The pro'cess is particularly applicable to efliuents in which the hydrocarbons present are paraflins in type; Thus it has particular advantage in the treatment of the eflluent from the isomerizatlonof normal paramns to isoparafiins since substantially the only hydrocarbons found in the efliuent'from such a process are paraflins including the isoparaffin product and unconverted normal paraffin.

However, the process may be applied to eiiluents from conversions other than paraffin isomeriaation. For example, it may be employed to purify the effluent from the metal halide-cataly zed alkylation' pf isoparafilns with low-boiling oleiins, where such eiiluent does not contain an undue amount of olefins. It will be understood that olefinsare very readily polymerized by phosphoric acids and so may be at least partially converted to the polymer in the treatment;

An example of another effluent which may be treated by the present invention is that from the cracking of high-boiling petroleum oils to make gasoline in .the presence of aluminum chloride \or the like and hydrogen chloride. Such an effluent contains little or no non-paraiiins and so -is very advantageously treated by-the process of my invention;

I prefer to apply my invent on to a vaporous eiiiuent, such as the vaporous effluent from the isomerization of normal butane to isobutane in the presence of aluminum chloride or bromide and the correspondin'ghydrogen halide; In such an application, I scrub the vaporous efiluent with the liquid phosphoric acid vfor example, in an absorber directly following; the catalyst cham-,

Since normal paramns and isoparafllns are unaffected by the phosphoric acid, the treated eflluent consists of the isoparafiin, the unconverted normal paramn, and any lighter paraflins the hydrogen halide. This mixture may be read ily treated by known methods to recover the hydrogen halide for recycle. I

By the foregoing treatment of the efiiuent, the

1 halide is removed by chemical reactionto form the corresponding metal tially by adsorption, absorption, etc.

The removal of the metal halide by chemical 'reaction involves the generation of the hydrogen halide coresponding to the metal halide catalyst. This is a distinct advantage since metal halide which might otherwise be wasted or lost is thus converted to hydrogen halide which is available for recycle as promoter for the conversion. This is especialiy advantageous where the metal halide entering the reaction is combined or dissolved in the form of a complex or sludge.

The temperature used in the purification treatment may vary widely. Where, as in the pre- However, it is perfectly possible when treating vaporous effluent, to operate the phosphoric acid absorption step at a temperature such that condensation, partial or complete, of the hydrocarbon content thereof takes place. As will be understood, whether condensation takes place or not and, if so, to what extent depend also upon the pressure maintained in the absorption step. This pressure may be substantially the same as that in the conversion step or it may be'materially higher or lower than said pressure by the use of suitable pressure increasing means (e. g. a pump or compressor) or pressure reducing means between the catalytic converter and the absorber. In practice it is preferred to carry out the absorption step at a lower pressure so that the temphosphate and also parferred embodiment, a vaporous eiiluent is being treated it is preferred to use temperatures sufilperature thereof may be correspondingly lower than that of eiiluent vaporsleaving the converter.

The absorber may, if desired, function as a cooler and/or a quencher for the vaporous efliuent where the said vapors are at a temperature materially higher than the phosphoric acid absorption medium. Thus the quenching, i. e. rapid cooling of the hot reaction efiluent, may serve to prevent re-reaction between the reaction prod.-

ucts,

vWhere a vaporous eilluent is treated in the absorber-in such manner that condensation of hydrocarbons contained in the efiluent occurs, layer separation is allowed to take place, preferably wards but preferably below the boiling point.

The treatment may be conducted in any apparatus known to be suitable for-lntimate liquidliquid contacting, followingwhich the separation of phases is made and the two separated phases,

. rmn c,further r s formed in the converter, and practically all of a ate and extra t p aces ed separately in any suitable way. a As an example of the invention, the vaporous effluent from the vapor phase isomerization of normal butane to isobutane at a pressure of .10 pounds per square inch gauge and a temperature of 210-250 F. overJump aluminum chloride and in the presence of hydrogen chloride as a promoter, is passed at said temperature and pressure from the converter through pressure-re- 76 ducing means andthen through a coolerto bring asoaee I it saidefiuent to a temperature approaching 100 F. while still maintaining the vapor phase. The gaseous eifluent is then scrubbed in an absorption unit at about 100 F. with 85% orthophosphoric acid which isat a temperature of 100 F. All of the aluminum chloride vapors and fines inthe vapors are removed. In addition the aluminum chloride complexes are broken down so that the efiuent contains no aluminum chloride either free or combined. "The scrubbed efliuent was in the vapor phase and consisted of isobutane, normal butane, virtually all of l the hydrogen chloride which left the isomerizer, and small quantities of lighter gases than C4 including propane.

After theabsorption medium is spent, it may be either discardedor repurified for reuse. This recovery may be carried out in anylsui'table manner known to the art to be practicable.

The process may be operated in either a batchwise or a continuous manner, thelatter being preferred. Thus the vapors leaving a continuously operated isomerization unit may be 'con tinuously passed to the-absorption unit into which fresh absorbing medium is continuously introduced. Rich or spent phosphoric acid is continuously withdrawn at the same rate as the fresh was introduced. The treated eiliuent is continuously passed in vapor form to a unit where the hydrogen chloride is continuously separated and a suitable portion or all thereof recycled. The unconverted normal butane maybe separated from the isobutane in the same or a separate unit and recycled for further conversion.

While an aluminum halide, namely either aluminum chloride, bromide or very infrequently, iodide, is most commonly used as the, catalyst in carrying out my invention, other metal halides mally either liquid or solid, usually the latter.

may be used. Examples are\the chlorides, bro-- mides or iodides of the, following metals:

Zinc vTitanium Tin Iron Arsenic Boron Antimony Beryllium, etc.

Zirconium tacting the reaction efliuent from a hydrocarbon conversion catalyzed by a metal halide of the Friedel-Crafts type in the presence of a hydrocatalyst therefrom without removing the hydro,= gen halide.

3. The process which comprises intimately contacting the reaction effluent from a hydrocarbon conversion catalyzed by a metal halide of the Friedel-Crafts type in the presence of a hydrogen halide which efiiuent contains a substantial amount of said catalyst and of said hydrogen halide in addition to hydrocarbon, with liquid aqueous orthophosphoric acid containing from 50 to 85% HaPO4 and thereby efiecting substantially complete removal of said catalyst therefrom without removing the hydrogen halide.

4. The process which comprises, intimately 0 ntacting the reaction eiiluent from a hydrocarbon conversion catalyzed by a metal halide of the Friedel-Crafts type in the presence of a hydrocomplete removal of said catalyst therefrom withgen halide which efliuent contain a substantial amount oi said catalyst and of said hydrogen halide in addition to hydrocarbon, with liquid orthophosphoric acid containing 85% HaP O4 and 15% of water and thereby effecting substantially out removing the hydrogen halide.

5. The process which comprises intimately contactiiig the reaction eiiiuent from a hydrocarbon conversion catalyzed by a'metal halideof the ,hydrogen halide.

Friedel-Craits type in the presence of a hydrogen halide which efliuent contains a substantial amount of said catalyst and of said hydrogen halide in addition-to hydrocarbon, with substantially anhydrous tetraphosphoric acid and thereby effecting substantially complet removal of said catalyst therefrom withoutremoving the 6.- The process of removing aluminum halide v from a vaporous efliuent from a hydrocarbon conof the Friedel-Crafts type and which are norgen halide which eflluen't contains a substantial amount of said catalyst andof said hydrogen halide in addition to hydroparbomwith -a-liquid phosphoric acid containing at'least 50% of phosphoric acid and thereby effecting substantially and vaporized aluminum halide, which comprises scrubbing said efliuent in the vapor phase with a liquid phosphoric acid containing at least 50% of phosphoric acid and thereby effecting substantially complete removal of aluminum halide therefrom without removing the hydrogen halide. '7. The process oi removing aluminum chloride from the eiiluent vapors resulting from theisomerization of normal butane to isobutane by means of aluminum chloride and hydrogen chloride, said eiiluent vapors containing volatilized aluminum chloride, normal butane, isobutane and hydrogen chloride, which comprises scrubbing-said effluentin the vapor phase andat an elevated temperature with a-liquid phosphoric acid containing at least 50% of phosphoric acid under such condition that all of the aluminum chloride c0ntentof the 'eiiluent is removed by reaction with said acid to form hydrogen chloride which appears in the scrubbed efliuent, and separately removing-:from the scrubbing zone the resulting liquid phase and the treated vaporous ei'fluent free from aluminum chloride and containing normal butane, isobutane and substantially all of the hydrogen chloride pre'sent in the original effluent vapors and formed from said aluminum Friedel-Crafts type in the presence of ahhydrogen halide which efiiuent contains a substantial amount of said catalyst and of 'said'hydrogen halide in addition to hydrocarbon, with "liquid aqueous orthophosphoric acid. containing at least 50'%'of orthophosphorlc acid and thereby effecting substantially complete removal of said chloride in said scrubbing step.

I 8. The process ofremoving volatilized aluminum chloride. from the eiliuent vapors re'sulting from the isomerization of normal butane to isobutane inthe presence of aluminum chloride and hydrogen chloride, which efliuent'contains a. volatilized aluminum 'chIoride normai butane, i'somaterial, other than hydrocarbon, is removed,

from aid eiliuent, and separately removing from the scrubbing zonethe resulting liquid phase and the treated vaporous efliuent free from aluminum 50% of phosphoric acid whereby said carry-over aluminum chloride is' removed from said eiiiuents by reaction with said phosphoric acid and hydrogen chloride is thereby produced, separating from the ,thusetreated eflluents the hydrogen chloride so produced and-the hydrogen chloride originally present, in saidefliuents and returning said hydrogen chloridewto the said reaction zone as catalyst promoter. e

l2. In a hydrocarbon conversion process wherein conversion is effected in the presence of aluminum chloride catalyst promoted with hydrogen chloride and wherein reaction zone effluents chloride and consisting of normal butane, isobutane, any lighter hydrocarbons formed in the isomerization step and substantially all of the v v hydrogen chloride present in the isomerization eilluent and formed from said aluminum chloride in said scrubbing step.

9. In a hydrocarbon conversion process wherein conversion is efiected in the presence of aluminum chloride catalyst promoted with hydrogen f chloride and wherein reaction zone eiiiuents carry over aluminum chloride, the improvement which comprises intimately contacting such effluents in a contacting zone subsequent to the reaction zone with 85% orthophosphori'c acid whereby said carry-over aluminum chloride is removed from said efl'luents by reaction with said orthophosphoric acid and hydrogen chloride is thereby produced, separating from the thustreated efiiuents the hydrogen chloride so produced and the hydrogen chloride originally present in said efiluentsand returning said hydrogen chloride to the .said reaction Zone as catalyst promoter.

10. In a hydrocarbon conversion .processwherein conversion is effected in the presence of aluminum chloride catalyst promoted with hydrogen chloride and wherein reaction zone effluents carry over aluminum chloride, the improvement'which comprises intimately contact-' ing such effluents in a contacting zone subsequentto the reaction zone with orthophosphoric acid having a concentration ranging from to 85% whereby said carry-over aluminum chloride is removed from said eflluents by reaction with said orthophosphoric acid and h'ydrogen chloride is thereby produced, separating from the thustreated efiiuents the hydrogen chloride so produced and the hydrogen chloride originally present in said eiiiuents andreturning said hydrogen chloride to the said reaction zone as catalyst promoter.

11. In a hydrocarbon conversion process wherein conversion is effected in the presence of aluminum chloride catalyst promoted with hydrogen chloride and wherein reaction zone eiiluent's carry over aluminum chloride, the improvement which comprises intimately contacting such efliuents in .a contacting zone subsequent to the reaction zone with a liquid phosphoric acid containingat least said hydrogen chloride to the said carry over aluminum chloride, the improvement which comprises intimately contactingsuch effiuents in a contacting zone subsequent to the reaction zone with substantially anhydrous tetra;' phosphoric acid whereby said carry-over 'alumi.

num chloride is removed from saidefiiuents by reaction with said tetraphosphoric'acid and hy- I drogen chloride is thereby produced, separating from the thus-treated eiiiuents the ..hydrogen chloride so produced and, the hydrogen chloride. originally present in said efliuents and returning said hydrogen chloride to the said reaction zone as catalyst promoter. v 13, In a hydrocarbon conversion process where- -in conversion iseflected in the'presence of aluminum chloride catalyst prorriot'ed with hydrogen chloride and wherefroln the reaction eiiiu'ents are withdrawn in vaporous form, which vaporous eiliuents carry over volatilized aluminum chloride,

the improvement which comprises intimately I contacting said vaporous efiluents in a contacting zone subsequent to the reaction zone' with-% orthophosphoric and whereby said carry-over aluminum chloride \is removed from said eflluents by reaction with said 'orthophosphoricacid and hydrogen chloride isfithereby produced, separating from the thus-treated eflluentsvthe hydrogen chloride so produced and the hydrogen chloride originally present in said eilluents, andreturning as catalyst promoter.

14. In the isomerization of normal butane to:

isobutane in the presence of aluminum chloride catalyst promoted with hydrogen chloride and wherefrom the. reaction efli-uents are withdrawn in vaporous form, which vaporous eiiiuents carry over volatilized aluminum chloride, theimprovement which comprises intimately contacting said vaporous efiluentsin a contacting zone subsequent to the reaction zone with 85% orthophosphoric and whereby said carry-over aluminum chloride is removed .from said 'eiiiuents by reaction with said orthophosphoric acid and hydrogen chloride so produced and the hydrogen chloride-originally present-in said efiluents, and returning said hydrogen chloride to the said reaction zone as catalyst promoter.

JOHN W. LATCHUM iR.

reaction zone 

